package main

import "encoding/json"
import "fmt"

type Condition struct {
	Or []interface{} `json:"$or"`
}

func main() {
	var c Condition
	c.Or = make([]interface{}, 3)
	c.Or[0] = "aa"
	c.Or[1] = ""
	c.Or[2] = "af"

	a, _ := json.Marshal(&c)
	fmt.Println(string(a))
}
